I recently acquired a police turn-in Glock 22 with 7 used magazines. I have shot it twice. The first time, it was a nice fall day, probably 60 degrees outside. I loaded each mag w/ 13 rounds of Winchester white box and shot using each mag 1 time. It ran flawlessly. I took it home, cleaned and lubed it, and put it away. Last week, I took the Glock out for the second time. The temp was 39 degrees. I decided to test some Federal HST 155gr rounds to make sure I could trust them in my Glock. I loaded each mag w/ 13 rounds of HST until I the 50rnd box was empty (one mag had fewer rounds). I had a scary number of feedway malfunctions (probably 15 out of the 50 rounds). Needless to say, I was pissed off. Then, I loaded 50rnds of Federal 180gr FMJ, and had a similar number of malfunctions. Where should I start trying to correct the problem? The two mags that had the highest number of malfunctions had a rev. 2 and 4 follower. The others were all rev 5. At first, I thought the sharpness of the HSTs was the cause (and they are sharp!), but the FMJs proved that theory wrong. I bought a new recoil spring, but haven't tried it (I figure it's a good idea to replace it either way).